The tiny Tumbling Creek cavesnail lives in one cave system in Missouri. Since 1974, its numbers have declined by 99%. Concern over dramatic population declines led to periodic counts by Dr. Ashley of Missouri Western State University beginning in 1996 and continuing to the present. The census results led to the emergency listing of the snail as endangered on December 27, 2001 and final listing as endangered on August 14, 2002.

Animals like the Tumbling Creek cavesnail that can live in cave environments are often highly adapted to that environment and as a result are not flexible in their tolerance of environmental changes. Declines or loss of these animals indicate a change in the cave ecosystem that they cannot tolerate. Often this change is degraded water quality. Above-ground land uses that affect water quality are being investigated as a source of this snail's population decline.